The invention relates to a test chamber in which objects to be tested can be exposed to an electromagnetic radiation field, or in which electromagnetic radiation emitted by objects to be tested can be measured, provided with means for coupling in/coupling out electromagnetic radiation and provided with means to distribute the electromagnetic radiation uniformly throughout the test chamber.
Test chambers of this type are known. They serve to verify the proper functioning of equipment exposed to a radiation field of predefined strength. Therefore, it is of importance to introduce a substantially uniform radiation field into the test chamber. A known and approved embodiment realizes a uniform radiation field by radiating a defined radiation field into one side of the test chamber and by absorbing the radiation at an opposite side. This embodiment has the drawback that high power levels are required which, particularly in case of high frequencies, is extremely costly. A further known and theoretically acceptable embodiment approximates a uniform radiation field by introducing a radiation field into a test chamber metallized on the inside and by subsequently creating an at least statistically uniform field by means of a stirrer. This method entails the drawback of being very time-consuming, because each measurement has to be averaged out during at least one stirrer revolution.
The inventive test chamber obviates this drawback to a significant extent and is characterized in that the test chamber possesses a reverberation chamber-geometry, that the test chamber walls are made of an electrically-conductive material, and that the means for the uniform distribution of the electromagnetic radiation are designed to move, in an operating mode, at least one part of a wall.
An advantageous embodiment according to an aspect of the invention that is relatively simple to realize is characterized in that the means for moving at least one part of a wall are designed to cause at least one part of a wall to vibrate.
An advantageous embodiment according to a further aspect of the invention is characterized in that the wall is made of a conductive fabric. This enables an apparatus to be field-tested with the test chamber built around the apparatus to be tested. This obviates the need to test the apparatus in a laboratory environment which causes a substantial reduction of expenses, since there are no cost arising from transportation or laboratory testing, the latter often requiring an environment comprising additional equipment, special-purpose cables, power supplies and the like.
An advantageous embodiment according to a further aspect of the invention is characterized in that the reverberation chamber is realized as a tent. In this embodiment, the conductive fabric can advantageously be provided with conductive slide fasteners, so that the tent can simply be set up around the apparatus to be tested. If required, it is possible to remove a part of the tent""s lower edge, causing it to abut against a metal plate or foil, preferably placed underneath the apparatus to be tested.
A further advantageous embodiment of the invention is characterized in that a frame is provided within which the reverberation chamber can be suspended from the frame""s corner joints. This embodiment, well-known in the field of tent constructions, entails the advantage that the test chamber does not require any supporting means.
A further advantageous embodiment of the invention is characterized in that the tent is provided with a connection for a pressure gas, for creating an overpressure in the tent. Also this embodiment, well-known in the field of tent constructions entails the advantage that the test chamber does not require any supporting means. Additional advantages in this respect are that the test chamber can be set up in a relatively short time and that the gas flow, usually air, ensures a good ventilation in the tent.
A further advantageous embodiment according to an aspect of the invention is characterized in that the means for moving at least one part of a wall are realized as a vibrator, in the operating mode attached to one of the tent""s corner joints. In an advantageous embodiment, drive means are provided for actuating, in the operating mode, the vibrator at a frequency of 5-20 Hz.